Apparatus and method for evaluating ligaments

ABSTRACT

The present invention is generally directed to apparatuses and methods for evaluating the amount of “play” in a joint. In one embodiment, an apparatus is provided that quantifies the rotation of the tibia in response to a known torque. The apparatus is configured to minimize the influence of other joints on the rotation analysis. Other embodiments provide data related to movement of the tibia in other degrees of freedom.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/271,712, filed May 7, 2014, and entitled “Apparatus and Method forEvaluating Ligaments,” which is, in turn, a continuation of U.S.application Ser. No. 12/797,324, filed Jun. 9, 2010, entitled “Apparatusand Method for Evaluating Ligaments”, which is a divisional of U.S.application Ser. No. 11/457,443, filed Jul. 13, 2006, now U.S. Pat. No.7,753,862, issued 2010 Jul. 13, entitled “Apparatus and Method forEvaluating Ligaments”, which claims the full benefit and priority ofU.S. provisional Application No. 60/699,003, filed Jul. 13, 2005,entitled “Apparatus and Method of Use for Determining Limb Rotation”,and U.S. Provisional Application No. 60/786,447, filed Mar. 27, 2006,entitled “Apparatus and Method For Evaluating Ligaments.” The entirecontents of all such applications are incorporated by reference intothis application.

FIELD OF THE INVENTION

The present invention relates to apparatuses and methods for evaluatingthe performance of a joint. More particularly, the present inventionprovides apparatuses and methods for quantifying the amount of movementallowed by a joint to aid in the diagnosis of and treatment for ligamentdamage.

BACKGROUND

The knee is composed of the femur or thigh bone, the tibia or shin boneand the patella or knee cap. They are connected by fibrous structurescalled ligaments which allow a certain amount of ‘joint play’ to existbetween the bone structures. When this ‘joint play’ is increased ordecreased an abnormal or pathological condition exists in the knee.Attempts have been made in the past to quantify this increase ordecrease in ‘joint play’ of the knee with limited success.

An injury to the knee can cause damage to one or more of the structuresof the knee causing an increase in the ‘joint play’ of the knee. Thisincrease in ‘joint play’ can create the sensation to the patient thatthe knee is slipping or ‘coming out of joint’. Commonly, this sensationdescribed by the patient is referred to as the feeling of ‘jointinstability’. The ability of the two bones to actually ‘come out ofjoint’ is related to the length of the fibrous structures or ligamentswhich connect the two bones together as well as the shape and size ofthe two bones (or three). The ability of the bones to ‘come out ofjoint’ or become unstable is related to the amount of stretch or theamount of increased lengthening of each ligament, the number ofligaments involved, and damage to other support structures of the kneesuch as the bone itself and the menisci. Accurate measurement of thisincreased ligament length is critical to restore the knee to as close toits original functional and anatomical state as possible.

Currently, there are only manual tests used by clinicians to aid in thediagnosis of ligament damage or increased (decreased) joint play. As anexample, there are three manual tests to evaluate the increased jointplay associated with an ACL tear—the Lachman's test, the Pivot Shifttest and the Anterior Drawer Test. All of these tests suffer from theclinician's subjective evaluation of both the extent of the ligamentlengthening and the change in the compliance or stretchiness of theligament.

The Lachman's test is perfolined by laying the patient in a supineposition and bending the knee at approximately 20 to 30 degrees. Theclinician places a hand on the patient's upper thigh and his other handbelow the upper part of the patient's calf muscle. Pressure is appliedunder the patient's calf and down on the patient's thigh such thattranslation between the tibia and femur occurs.

Similar to the Lachman's test, the pivot shift test begins bypositioning the patient on his back. The knee is flexed (x-axisrotation) and a valgus (z-axis rotation) force and an internal rotation(y-axis rotation) force is applied to the knee as the knee is broughtinto full extension (x-axis rotation). The clinician feels for anabnormal internal rotation (y-axis rotation) and anterior translation(z-axis translation) of the tibia with respect to the femur. This shiftis felt to represent the relative increased translation (z-axistranslation) of the lateral side of the knee with respect to theincreased translation (z-axis translation) of the medial side of theknee. Furthermore, the point of sudden shift represents the point atwhich the back part of the tibia bone slides in front of the radius ofcurvature of the curved end of the femur. The clinician subjectivelyrates the pivot shift as Grade I, Grade II or Grade III depending uponthe degree of rotational and translational shift felt during the test.This test is difficult to perform, difficult to teach and difficult toquantify.

Finally, the anterior drawer test is performed with the patient lying onhis back and his knee bent to 90 degrees. With the patient's footsupported by a table or chair, the clinician applies pressure to theknee using her thumbs. This test is graded based upon the amount orextent of anterior translation along the z-axis of the tibia withrespect to the femur. Grade I has 0 to 5 mm of anterior translation(z-axis translation), Grade II has 6 to 10 mm of anterior translation,and Grade III has 11 to 15 mm of translation.

To diagnose an injured ACL using the described tests, the clinician mustdetermine whether the knee feels “abnormal.” Thus, the accuracy of anACL injury diagnosis using currently known tests depends on the skilland experience of the clinician. A misdiagnosis can lead to unnecessarydelay in treatment, thereby placing the patient at increased risk forfurther damage to the knee.

There are manual tests for the LCL, MCL and the PCL. Each manual testrelies on grading the extent of the ligament lengthening into threecategories. There is no effort to grade the compliance of the ligament;however, the expert clinician will describe the ligament in terms of its‘feel’. The more ligaments and structures that are damaged; the morecomplex it becomes to perform a knee examination using the subjectivemanual exams.

There have been multiple attempts in the past to instrument the knee andquantify or measure the change in the structure of the knee afterligament damage. Only one device has attempted to accurately quantifythe extent or relative displacement and compliance a ligament in theknee. The KT-1000 and the KT-2000 Medmetric® by measure theanterior-posterior translation of the tibia with respect to the femuralong the z-axis. These devices attempt to quantify the findings foundwhen the clinician uses the Lachman's test and the Anterior Drawer Test.Force is applied to a handle on the device which measures force andsignals to the clinician the amount of force with a low pitched soundfor the 15 pound force, a higher pitched sound for the 20 pound force.This force pulls anteriorly along the z-axis through a strap that wrapsunderneath the calf. The measurement of the translation uses a techniquemeasuring the relative motion of a pad on the anterior tibia withrespect to a pad placed on the patella. This device does not measurerelative displacement or compliance in any of the other degrees offreedom previously described in the knee. Furthermore, the quantifiedresults of the KT-1000 or KT-2000 have not been correlated with patientsatisfaction where as the subjective Pivot Shift test has bee correlatedwith patient satisfaction.

Accordingly, there is a need for an accurate, objective, reliable andreproducible measure of the impact of damage to the ACL as well as otherligaments and structures in the knee that can be used in the clinicalsetting on patients. For example, since an injury to the ACL producesboth an increase in anterior translation (z-axis translation) androtation (y-axis rotation), an objective measure of these changes wouldboth aid in the diagnosis of the injury as well as verify itsrestoration after ligament reconstruction surgery. Additionally,measurement of displacement and compliance around different degrees offreedom in the knee would help objectively describe the individual andcomplex changes to ‘joint play’ that occur with an injury to the knee. Aneed exists for systems and methods that can provide accurate,reproducible and objective data on the changes in ‘joint play’ thatoccur with an injured knee compared to their noinial knee and to thepopulation as a whole such that the clinician can achieve patientsatisfaction with focused, biomechanical and proven surgicalinterventions individualized for that injury and for that knee acrossthe entire population of damaged knees.

SUMMARY OF THE INVENTION

The following summary is not an extensive overview and is not intendedto identify key or critical elements of the apparatuses, methods,systems, processes, and the like, or to delineate the scope of suchelements. This Summary provides a conceptual introduction in asimplified form as a prelude to the more-detailed description thatfollows.

The above and other needs are met by the present invention whichprovides apparatuses and methods for evaluating the amount of play in ajoint.

In one aspect of the invention, an apparatus for evaluating therotational performance of a patient knees is provided where the patienthas two legs and each leg has a femur, knee, tibia, ankle and a foot.The apparatus includes: a frame having a base configured to be placed ona support surface and a support column attached relative to the base andextending substantially perpendicular there from; a transverse memberattached relative to the support column within a plane substantiallyparallel to the base and perpendicular to the support column; a firstpivot assembly attached relative to the transverse member and configuredto transfer a torque to a first tibia of the patient by rotating anassociate first foot about an axis substantially aligned with thelongitudinal axis of the first tibia; a first angle measuring deviceattached relative to the first assembly and configured to measureangular displacement of the first pivot assembly in response to thetorque; a second pivot assembly attached relative to the transversemember and configured to transfer a torque to a second tibia of thepatient by rotating an associate second foot about an axis substantiallyaligned with the longitudinal axis of the second tibia; and a secondangle measuring device attached relative to the second pivot assemblyand configured to measure angular displacement of the second pivotassembly in response to the torque.

In another aspect of the invention, an apparatus for evaluating therotation performance of a patient's knees is provided. The apparatusincludes: a frame having a cross member attached relative to a spinemember; a plurality of thigh positioning posts releaseably attachedrelative to said cross member and configured to secure said two thighsof the patient; a carriage configured to move along at least a portionof the length of the spine member; a first pivot assembly attachedrelative to the carriage and configured to transfer a torque to a firsttibia of the patient by rotating an associate first foot about an axissubstantially aligned with the longitudinal axis of the first tibia; afirst angle measuring device attached relative to the first assembly andconfigured to measure angular displacement of the first pivot assemblyin response to the torque; a second pivot assembly attached relative tothe carriage and configured to transfer a torque to a second tibia ofthe patient by rotating an associate second foot about an axissubstantially aligned with the longitudinal axis of the second tibia;and a second angle measuring device attached relative to the secondpivot assembly and configured to measure angular displacement of thesecond pivot assembly in response to the torque.

In a further aspect, an apparatus for evaluating the performance of apatient's knee in two degrees of freedom is provided. The apparatusincludes: a frame having a cross member attached relative to a spinemember; a plurality of thigh positioning posts releaseably attachedrelative to the cross member and configured to secure the thigh of thepatient; a carriage configured to move along at least a portion of thelength of the spine member; a first pivot assembly pivotably attachedrelative to the carriage and configured to transfer a torque to thetibia causing movement of the tibia relative to the femur in a firstdegree of freedom; a first angle measuring device attached relative tothe first pivot assembly and configured to measure angular displacementof the first pivot assembly in response to the torque; a second pivotassembly pivotably attached relative to the carriage and configured totransfer a second torque to the tibia causing movement of the tibiarelative to the femur in a second degree of freedom; and a second anglemeasuring device attached relative to the second pivoting assembly andconfigured to measure angular displacement of the second pivot assemblyin response to the second torque.

In another aspect of the invention, a method for evaluating theperformance of a knee of a patient is provided. This method includes thesteps of: positioning a patient supine with the knee bent; positioningthe foot into an AFO rotatably attached to a frame such that the axis ofrotation of the AFO is in substantial alignment with the longitudinalaxis of the tibia; rotating the AFO by applying a torque; capturing datarelated to the rotation of the AFO.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is an illustrative view of a patient's legs and a portion of anembodiment of the present invention. This view may be considered a sideplan view of a patient in a supine position looking at the patient'sright side.

FIGS. 2 and 4 are illustrative views of a patient's legs and a portionof embodiments of the present invention. These views may be considered aview looking down on a patient in a supine position.

FIG. 3 is a illustrative view of a patient's feet showing internal (“I”)and external (“E”) rotation of the feet and associated tibia (not shown)in accordance with an embodiment of the present invention.

FIG. 5 is a drawing illustrating apparatus 10, which is an embodiment ofthe present invention.

FIG. 6 is a drawing illustrating apparatus 10, which is an embodiment ofthe present invention. This view may be considered a side view of theapparatus 10.

FIG. 7 is a drawing illustrating a portion of apparatus 10 including apivoting assembly 50.

FIG. 8 is section view of the socket 55 and conversion socket 58 therebyexposing the shaft 53 in accordance with an embodiment of the presentinvention.

FIG. 9 is a section view of the bushing retainer 51, bushing 52, andcollar 54 thereby exposing the socket socket 55 and a portion of theshaft 53 in accordance with an embodiment of the present invention.

FIG. 10 is a drawing illustrating the angle measurement device 60 inaccordance with an embodiment of the present invention.

FIG. 11 is a drawing of the angle measurement device 60 in FIG. 10 withthe pivoting assembly rotated clockwise to illustrate the effect on theangle measurement device 60.

FIG. 12 is drawing of folding assembly 70 in accordance with anembodiment of the present invention.

FIG. 13 is a drawing of a portion of the folding assembly 70illustrating exemplary plate bracket 84 a.

FIG. 14 is a drawing showing a folding assembly 70 partially folded inaccordance with an embodiment of the present invention.

FIG. 15 is a drawing illustrating apparatus 100 in accordance with anembodiment of the present invention.

FIGS. 16 and 17 are illustrative drawings of a portion of a patient anda portion of apparatus 100 in accordance with an embodiment of thepresent invention

FIG. 18 is a flow chart illustrating steps of an exemplary method inaccordance with an embodiment of the present invention.

FIG. 19 is a screen shot of a data analysis tool in accordance with anembodiment of the present invention.

FIG. 20 is a drawing illustrating a top view of pivoting assembly 200 inaccordance with an embodiment of the present invention.

FIG. 21 is a drawing illustrating a side view of pivoting assembly 200in accordance with an embodiment of the present invention.

FIG. 22 is a drawing illustrating the multi-axis pivoting assembly 200in accordance with an embodiment of the present invention.

FIG. 23 is a drawing illustrating a torodial restraint for use with anembodiment of the present invention.

FIG. 24 is a drawing illustrating an adjustable thigh support 180, aspine 130 and a cross member 114 a in accordance with an embodiment ofthe present invention.

FIGS. 25 and 26 illustrate a breakaway coupling in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present inventions now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the inventions are shown. Indeed, these inventions may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

General Construction and Operation

Generally described, embodiments of the present invention provide noveldevices and methods to evaluate joints. More particularly, embodimentsof the present invention provide a clinician with movement, “joint play”data for a joint to assist in diagnosing ligament damage or inevaluating the effectiveness of treatment for a damaged ligament. In thefollowing paragraphs, an embodiment of the present invention will bedescribed with relation to evaluating a knee joint; however, as one ofordinary skill in the art will appreciate, the concepts disclosed hereinmay be used to evaluate any other joints such as an elbow, shoulder andwrist.

The ‘joint play’ between the femur or thigh bone and the tibia or shinbone (and fibula) can be described by breaking down the motion into theusual six degrees of freedom. If the x-axis is situated such that itextends along the lateral to medial aspect of the right tibia, they-axis should extend along the superior-inferior aspect of the righttibia and the z-axis should extend anterior-posterior in the right tibiaas generally shown in FIGS. 1 and 2. Data related to four degrees offreedom may be useful in evaluating the joint play of the knee or tibiawith respect to the femur. One of these degrees of freedom is rotationaround the x-axis. This represents extension or straightening of theknee and flexion or bending of the knee to describe range of motion ofthe knee. The other three degrees of freedom are: rotation around thez-axis, rotation around the y-axis and translation at the z-axis.

Movement along these degrees of freedom stress the four primaryligaments in the knee which connect the thigh bone to the shin bones—themedial collateral ligament (MCL), the lateral collateral ligament (LCL),the posterior cruciate ligament (PCL) and the anterior cruciate ligament(ACL). The MCL is generally located on the side of the knee next to theother knee and connects the femur to the tibia. The LCL is generallylocated on the other side of the knee away from the other knee andconnects the femur to the fibula (the fibula is directly connected tothe tibia in the shin bone area). The ACL is generally located on theinside of the knee and connects between the femur and the tibia. The PCLis generally located on the posterior side of the knee and connectsbetween the femur and the tibia.

Translation at the z-axis in the anterior direction stresses the ACL,while translation in the z-axis in the posterior direction stresses thePCL. Rotation at the z-axis in the right knee in the clockwise directionstresses the MCL and causes the tibia to rotate the knee into a ‘knockknee’ position, while rotation at the z-axis in the right knee in thecounterclockwise direction stresses the LCL and causes the tibia torotate into a ‘bow legged’ position.

Rotation about the y-axis represents a global measurement of theintegrity of the knee including the shape of the femur as it sits intothe shape of the proximal tibia, the presence or absence of theassociated menisci within the knee, the integrity of the ligaments, andthe integrity of the entire soft tissue sleeve of the knee.

The ACL is composed of three bundles, the posterolateral bundle (PLB),the intermediate bundle (IB), and the anteromedial bundle (AMB). Currentresearch suggests that each of the bundles becomes stressed withanterior translation along the z-axis depending upon the positionflexion or extension of the knee (rotation around the x-axis of theknee). The PLB is felt to control anterior translation along the z-axiswhile the knee is in or near full extension and the AMB is felt tocontrol the anterior translation along the z-axis while the knee is inor near full flexion.

Embodiments of the present invention provide the clinician withapparatuses and methods to quantify the joint play for movement in oneor a combination of the degrees of freedom discussed above. Using thisdata, a clinician can assess the integrity of the ligaments in the knee.Also, by comparing the data for a single patient against a largerpopulation or comparing one knee to the other, abnormalities can beidentified.

Tibia Rotation Embodiments

FIGS. 1-4 illustrate an embodiment of the present invention forgathering rotational data relating to a patient's lower leg to evaluateligaments in the knee. It should be understood by those skilled in theart that concepts described below could be used to evaluate ligaments inthe shoulder, elbow, wrist or any other joint.

Referring specifically to FIGS. 1 and 2, a patient 2 having two legs 3a,b with each leg having a thigh (or femur) 4, a knee 5, a shin (ortibia) 6, an ankle 7 and a foot 8 is positioned supine on a supportsurface such as a examining table or the floor. To minimize rotation atother joints of the leg, the patient's thighs 4 are extended upwardlyand secured to a spacer 45. The patient's knee is bent to approximately30 degrees of flexion; however it should be understood that thepatient's legs could be flexed at any desired angle such as withoutlimitation, 45 degrees, 60 degrees, 90 degrees or 120 degrees.

In the illustrated embodiment, both thighs 4 are secured to a spacer 45using a strap 48. The spacer 45 is generally configured to hold thethighs 4 spaced apart such that the longitudinal axis if each tibia 6 issubstantially aligned with the rotational axis of the ankle footorthosis 57.

The patient's legs 3 a,b are bent at the knee with the feet beingsecured into ankle foot orthosis (“AFO”) using one or more straps (notshown). As will be understood by those skilled in the art, an AFO is abrace worn on the lower leg and foot to support the ankle, and it holdsthe foot and ankle in a desired position. In the illustrated embodiment,the AFOs are configured to pivot about an axis that is substantiallyparallel to the longitudinal axis of the patient's tibia 6. Thisarrangement contributes to more repeatable angular measurements becauserotational movement is substantially isolated at the knee joint. Theterm AFO as used herein is to be interpreted broadly to include anyknown or developed device that restricts movement at the ankle such asan ankle brace or boot type structure.

Referring specifically to FIG. 3, internal (“I”) and external rotation(“E”) of the tibia (i.e. shin bone) can then be measured usinginstruments attached to the AFOs. These angular measurements can betaken with or without applying a known torque to the AFOs and thereforethe tibia of the patient.

Exemplary Apparatus 10

An exemplary embodiment of the present invention, apparatus 10, is shownin FIG. 5. Generally described, apparatus 10 includes a base assembly20, a support column 30, spacer support assembly 40, traverse member 47and two rotating assemblies 50 a, b.

The base assembly 20 is configured to be placed on a horizontal supportsurface such as an examining table or floor. In the illustrateembodiment, the weight of the device and friction between the baseassembly 20 and the support surface provide stability to the device whenin use. However, it should be understood that the stationary baseassembly 20 may be secured to the support surface using straps, clamps,fasteners or any other securing means to provide additional stability.

This stationary base assembly 20 is substantially rigid and includes abase plate 21 and a substantially “H” shaped base frame assembly 22. Thebase plate 21 is substantially rectangular with an upper and lowersurface. The lower surface is configured to be placed on a supportsurface and the base frame assembly 22 is rigidly attached to the uppersurface.

The base frame assembly 22 includes two elongate members 23 a,b that arespaced apart and substantially parallel. Intermediate the elongatemembers is a cross member 24 that is oriented substantiallyperpendicular to the elongate members and rigidly attached to theelongate members 23 a,b near their midpoint. To increase rigidity,additional cross members 24 and elongate members 23 may be added. Itshould be understood that the base frame assembly 22 may be configuredin any desirable shape such as for example a “T” shape, a triangle, asquare, a rectangle, an octagon or a pentagon. Of course, the stationarybase assembly may only include a base plate without the additionalmembers or a base frame assembly without the base plate.

Extending up from the stationary base assembly 20 is the support column30. The support column 30 is an elongate member extending upwardsubstantially perpendicular from the cross member 24 of the stationarybase assembly 20 and includes a stationary portion 32 and a slidingportion 33. The stationary portion 32 is rigidly attached to the crossmember 24 of the stationary base assembly 20. To accommodate differingleg lengths between patients, the sliding portion 33 of the supportcolumn 30 may be slid along at least a portion of the length of thestationary portion 32 and releaseably locked at desired location usinglocking knob 34 such that the overall length of the support column 30 isadjusted. Preferably, the height of the support column 30 is adjustedsuch that the patient's knees are flexed at approximately 30 degrees andthe patient's tibias (or shins) are substantially parallel with therotating axis of the pivoting assemblies 50 a,b, which in thisembodiment is substantially parallel with the support surface. It shouldbe understood, however, that the support column 30 may be adjusted toany height desired by the clinician to gather a desired data set.Furthermore, as will be appreciated by those of skill in the art, thesupport column 30 of the present invention may be an elongate memberwithout a length adjustment. In this case, the patient may be raised orlowered in relation to the structural base assembly to achieve thedesired height.

Attached to one end of the adjustable support column 30 is the spacersupport assembly 40. The spacer support assembly 40 positions a spacerbetween the thighs of a patient such that the thighs can be securedtogether. As will be discussed in greater detail below, securing thethighs of the patient reduces the influence of the femur on the measuredrotation at the knee joint.

Referring to FIG. 6, the spacer support assembly 40 includes ahorizontal member 41, a spacer bar 44 and a spacer 45. The horizontalmember 41 includes a stationary portion 42 and an adjusting portion 43.As with the support column 30, the horizontal member's length can beadjusted as desired by the clinician. The adjusting portion 43 slidesalong and extends out from the stationary portion 42 until the desiredlocation of the spacer 45 is achieved. The adjusting portion 43 is thenreleasably secured to the stationary portion 42 using locking knobs 46.Of course, the horizontal member 41 may be elongate without a lengthadjustment. To facilitate discussion of the spacer support assembly 40,pivoting assembly 50 a is not shown in FIG. 6.

Referring to FIGS. 5 and 6, the horizontal member's length and thesupport column's length are adjusted such that the patient's knee isbent at approximately 30 degrees and the patient's tibias aresubstantially aligned with the rotation axis of the pivoting assemblies50 a,b. However, a person of skill in the art will appreciate that thesemembers may be adjusted as desired by the clinician to achieve a desiredorientation

Pivotably attached to the end of the horizontal member 41 is the spacerbar 44 as generally shown in FIG. 6. The spacer bar 44 pivots to allowthe spacer 45 to be positioned intermediate the thighs of a patient.Alternatively, the spacer bar 44 may be rigidly attached to thehorizontal member 41.

The spacer 45 is generally rectangular and preferably constructed of afoam type material such as polystyrene. A suitably sized recess isformed in the spacer 45 to receive one end of spacer bar 44. In use, thespacer 45 is positioned between the thighs of the patient near the kneejoint and aids in aligning the tibia of the patient with the rotationalaxis of the associated pivoting assembly as will be discussed in greaterdetail later. To accommodate variations in thigh diameter betweenpatients, spacers 45 of different sizes may be utilized. For example, aperson with relatively small diameter thighs will require a largerspacer versus someone having relatively large diameter thighs in orderto achieve the desired alignment.

Referring to FIG. 5, a transverse member 47 is also attached relative tothe end of the support column 30. The traverse member 47 is elongate andprovides support for the pivoting assemblies 50 a,b, which will bediscussed in greater detail later. The transverse member 47 is orientedsubstantially perpendicular to support column 30 and the horizontalmember 41 and rigidly attached, proximate its midpoint, to the supportcolumn 30.

Pivoting Assemblies 50 a, b

The apparatus 10 includes two pivoting assemblies 50 a,b spaced apartand secured to the transverse member 47. The spacing between thepivoting assemblies provides clearance to rotate the assemblies. As oneof ordinary skill in the art will appreciate, the spacing between thepivoting assemblies may be adjustable along the longitudinal length ofthe transverse member 47 such that the pivoting assemblies can bealigned with the natural spacing between the patient's feet.

FIG. 7 illustrates details regard the construction of pivoting assembly50 a. Pivoting assembly 50 b is configured the same as pivoting assembly50 a. Pivoting assembly 50 a includes a bushing retainer 51, a bushing52, a shaft 53, a collar 54, a socket 55, a conversion socket 58, anattachment bracket 56, an ankle-foot orthosis (AFO) 57 and an anglemeasuring device 60.

The pivoting assembly is attached to the transverse member 47 by abushing retainer 51. The bushing retainer 51 is substantiallyrectangular with a suitably sized aperture configured to accept thebushing 52 such that the bushing does not rotate when inserted.

The bushing 52 is substantially cylindrical with a suitably sizedaperture configured to accept the substantially cylindrical socket 55.As one of ordinary skill in the art will appreciate, the bushing 52 maybe of any suitable material such as, without limitation, plastic, metalor aluminum. The bushing facilitates smooth rotational movement whilerestricting movement perpendicular to the axis of rotation. It should beunderstood that the bushing 52 may be replaced with a pin, needle orball type bearing.

Referring to FIG. 8, the socket 55 has a cylindrical shape with a firstend and a second end. In one embodiment, the first end includes a squareaperture having an axis parallel with the longitudinal axis of thesocket 55 and configured to facilitate the application of a torque tothe pivoting assembly 50. The second end of the socket includes ahexagonal cavity that extends at least a portion of the elongate lengthof cylindrical socket 55. Socket 55 is similar to what is commonlyreferred to as a “deep well socket.” The hexagonal cavity is configuredto receive a first end of the shaft 53, which has a suitably sizedhexagonal cross section. The shaft 53 is rigidly attached to the socket55 using any known means such as without limitation adhesives orwelding. In the illustrated embodiment, the second end of the shaft 53extends beyond the second end of the socket 55; however, as will beunderstood by those of skill in the art, the second end of the shaft 53may be flush with the second end of the socket 55 or recessed in thesocket as desired.

As shown in FIGS. 7 and 9, the first end of the socket 55 extends outfrom the bushing 52, and a collar 54 is attached to the socket's outerdiameter intermediate the socket's first end and the edge of the bushing52. The collar 54 is secured to the socket using a set screw (notshown), and when secured, it resists axial movement of the socket 55 inthe bushing 52.

Any type of torque applying device may be utilized with embodiments ofthe present invention. For example, a torque wrench may be used toengage the square aperture formed in the first end of the socket. In analternative embodiment, a stepper motor is used to apply torque to thepivoting assembly. The stepper motor may be programmed to incrementallyincrease the rotation angle of the shaft until a predetermined torque isreached. With each incremental rotation, the torque is measured. Themotor stops when a maximum torque threshold is reached. At this point,the angle may be captured. When using a stepper motor, it is advisableto also use a safety device such as clutch that disengages the motorwhen a predetermined maximum torque is reached.

In FIG. 25, an exemplary break away coupling is illustrated that may beused in connection with embodiments of the present invention. Thiscoupling 700 includes an input shaft 710, an output shaft 720 and a pin725. The input shaft 710 is substantially cylindrical and is attached tothe drive shaft of a motor. The input shaft 710 defines a hole 711passing through a portion of the input shaft. The output shaft 720includes a first diameter portion 721 and a second diameter portion 722.The first diameter 721 portion defines a bore sized to accept the inputshaft 710. The first diameter portion also defines two holes 723 sizedand oriented to accept the breakaway pin 725. The second diameterportion 722 is configured to engage the socket. As will be understood bythose of skill in the art, the holes in the output shaft and the holesin the input shaft align to receive the shaft and need not pass throughthe longitudinal axis of the shafts.

In use, the input shaft 710 is positioned inside the bore of the outputshaft 720 and the breakaway pin 725 engages the holes defined by boththe input and output shafts as generally shown in FIG. 26. Thisfacilitates transfer of torque from the input shaft 710 to the outputshaft 720. When the torque exceeds a predetermined threshold, the pinbreaks allowing the input shaft 710 to spin freely. The breakaway pin725 may be sized differently to achieve different breakaway torques ormay be weaken with necked portion of notched portions to achievediffering torque thresholds as will be understood by those of skill inthe art. This will allow a clinician to customize the threshold torqueas desired.

As will be appreciated by those of skill in the art, other safetydevices may also be used such as fuse or breakaway coupling.

In addition, it should also be understood that other types of motors maybe used in connection with the present invention.

To facilitate use of different torque application devices, a conversionsocket 58 may be used to facilitate connection to the socket. Conversionsockets are well known and allow, for example, a torque wrench with a ¼″protrusion to drive a socket with a ⅜″ aperture. However, it should beunderstood that torque may be applied directly to the socket 55 withoutthe use of a conversion socket if the torque device and the socket driveaperture (or protrusion) are suitably sized.

In an alternative embodiment, the shaft 53 has a circular cross sectioninstead of hexagonal and the shaft diameter is suitably sized tocooperate with the bushing directly without the aid of the socket 55. Tofacilitate the application of torque, the end of the shaft may beconfigured with a recess sized to accept the protrusion of a torqueapplication device or may include flats that may be engaged by a torqueapplication device.

Returning to FIG. 7, the second end of the shaft 53 is rigidly attachedto the attachment bracket 56, which itself is attached to an ankle-footorthosis (AFO) 57. Thus, a torque is applied to the socket 55 orconversion socket 58 is transferred to the associated AFO 57 causing theAFO 57 to rotate.

Generally described, the AFO 57 is a brace that secures the lower legand the foot of the patient thereby restricting movement of the ankle.As will be understood by those of skill in the art, the lower leg andthe foot of the patient are preferably secured to the AFO using one ormore straps. In the illustrated embodiment, the AFO holds the ankle in aneutral position (no plantar flexion); however, as will be appreciatedby one of ordinary skill in the art, the AFO may be configured to holdthe patient's foot in any angle desired by the clinician.

The attachment bracket 56 is generally “L” shaped with a first leg and asecond leg. The first leg is secured to the lower leg portion of the AFO57 while the second leg is secured to the foot portion of the AFO 57.Additionally, the second leg is also secured to the second end of theshaft 53. In use, the axis of rotation of the pivoting assembly 50 isgenerally aligned with the proximate location of longitudinal axis ofpatient's tibia.

Referring to FIGS. 7, 10 and 11, rotation angles or angular displacementare determined using the angle measuring device 60, which is secured tothe second leg of the generally L shaped attachment bracket 56. Asillustrated, the angle measurement device 60 is in substantial alignmentwith the centerline of the AFO; however as one of ordinary skill in theart will appreciate, the angle measurement device does not have to bealigned with the attachment bracket and AFO.

In the illustrated embodiment, the angle measuring device 60 indicatesthe rotation angle of the associated AFO with respect to gravity. Thesetypes of devices are often called inclinometers. Generally described, aninclinometer includes an arcuate scale having indicia of degrees(similar to a protractor) and a pointer that continually indicates thedirection of gravity. As generally shown in FIG. 10, the arcuate scalerotates with the attachment bracket (and associated AFO), but thepointer continues to point in the direction of gravity. The resultingrelationship between the pointer and the arcuate scale is the rotationangle with respect to gravity for the AFO. In should be understood thatalternative methods of determining the angle of rotation may utilized inconnection with the present invention such as, without limitation,digital levels, digital inclinometers, or potentiometers.

Preferably, the neutral position of the AFOs is in alignment with thesupport column 30 and the support column is aligned with the directionof gravity and therefore, the neutral position of the pivotingassemblies will register zero degrees on the angle measuring device 60.To verify the alignment of the support column, an angle measurementdevice may be secured to the support column itself. Using this anglemeasurement device in connection with conventional leveling techniques,the support column may be brought into alignment with the direction ofgravity. Alternatively, the angle value taken from the angle measurementdevice on the support column can be used as an offset value for theangular measurements of the pivoting assemblies. In a furtherembodiment, the angle measurement devices on the pivoting assembliesthemselves are used to determine an offset value. In this embodiment,the pivoting assemblies are placed in a neutral position and theresulting measurements on the angular measurement devices attached tothe pivoting assemblies are used as an offset value as well. As one ofordinary skill in the art will appreciate, the angle measuring device 60may be zeroed at neutral position.

Exemplary Apparatus 70 (Folding Apparatus 2)

FIG. 12 illustrates an alternative apparatus 70 that has the ability tocollapse when not in use to facilitate transport and storage. Generallydescribed, this embodiment employs a folding frame assembly 80 in placeof the base frame 20 and support frame 30 as described with reference toapparatus 10. Specifically, the apparatus 70 includes a folding frameassembly 80, a spacer support assembly 40, a transverse member 47 andtwo pivoting assemblies 50 a,b.

The folding frame assembly 80 includes a substantially “T” shaped baseassembly 81, that is configured to be placed atop a support surface, twovertical supports 82 a,b and a horizontal bar 83.

The vertical supports 82 a,b are generally parallel to each other andare pivotably attached relative to the “T” shaped base assembly 81. Afirst vertical support 82 a is attached to what could be referred to asthe bottom of the “T” shaped base assembly while the second verticalsupport 82 b is attached to what could be referred to as the top of the“T” shaped base assembly.

Plate brackets 84 a,b are rigidly attached to the base assembly andrestrict the pivoting action of the first vertical support 82 a.Referring now to FIG. 13, a description of plate bracket 84 a isprovided. Plate bracket 84 a is rigidly attached to base assembly 81. Apin 86, attached to the vertical support 82 a, cooperates with anarcuate slot 85 defined by the plate bracket 84 a to limit the pivotingaction of vertical support 82 a to substantially between 0 and 90degrees. A locking pin (“P”) secures the vertical support in a positionsubstantially perpendicular to the plane defined by the base assembly81. An aperture defined by the bracket 84 a and a corresponding aperturedefined by the vertical support 82 a are aligned and suitably sizedlocking “P” is inserted into both apertures to lock the vertical support82 a into place. In alternative embodiments, a locking knob is attachedto the pin 86 extending into the accurate slot such that the pivotingangle with respect to the base 81 may be secured at any anglesubstantially between 0 and 90 degrees. Plate bracket 84 b is similar toplate bracket 84 a.

Attached to the opposite ends of the vertical supports 82 a,b ishorizontal bar 83. This bar is pivotably attached to each of thevertical support members such that the vertical supports 82 a,b, thebase assembly 81 and the horizontal bar 83 form a rectangle. Inalternative embodiments, the shape created by the connection of thesefour components is a parallelogram, or trapezoid.

Attachment of the horizontal bar 83 to the vertical support 82 b isfacilitated by plate brackets 84 c and 84 d (not shown). These bracketsdefine an arcuate slot that cooperates with a pin attached to thehorizontal bar 83 to restrict the pivoting action of the horizontalmember as generally described with reference to FIG. 13.

Additionally, the plate brackets 84 c,d and the horizontal bar 83 eachdefine apertures that align when the relative orientation of the twomembers is substantially 90 degrees. The apertures are suitably sized toaccept a locking pin (not shown), which secures the two members in asubstantially 90 degree relationship, as generally described withreference to FIG. 13.

The spacer support assembly 40 is attached relative to the horizontalbar 83 such that the longitudinal axis of the spacer support assembly 40is substantially parallel with the horizontal bar's longitudinal axis.The transverse member 47 and the pivoting assemblies 50 a,b areconfigured the same as described earlier with reference to apparatus 10.

In the embodiment illustrated in FIGS. 12 and 14, the horizontal member83 is not adjustable along its elongate axis; however, as one of skillin the art will appreciate, it could be adjustable as discussed withreference to apparatus 10.

When a data gathering session is complete, this embodiment of thepresent invention may be folded to a more compact size to facilitatetransport and storage as generally illustrated in FIG. 14. The apparatus70 may be collapsed by removing the locking pins (not shown) therebyallowing the vertical supports 82 a,b to pivot together. In oneembodiment, the apparatus 70 may be secured in the folded configurationusing a locking pin and cooperating apertures in the plate brackets.

Referring briefly to FIG. 8, the footprint of the folded assembly may befurther reduced by removing the pivoting assemblies 50 a,b by looseningthe set screw in the collar 54 and sliding the socket 55 and shaft 53out of the bushing 54 towards the AFO 57.

Exemplary Apparatus 100

As with the preceding apparatus 10 and 70, apparatus 100 facilitatescollection of rotational data with respect to a patient's tibia. FIG. 15illustrates apparatus 100, which includes a frame assembly 110 and apair of pivoting assemblies 150 a,b. The pivoting assemblies 150 a,b areconfigured similarly to those discussed with reference to FIG. 7. Frameassembly 110 is configured to support the pivoting assemblies 150 a,band position the patient to facilitate rotational data collection usingthe pivoting assemblies 150 a,b.

FIGS. 16 and 17 illustrate a portion of a patient 2 and a portion ofapparatus 100. Patient 2 is positioned supine on a support surface suchas an examining table or the floor. The patient has two legs 3 with eachleg having a thigh (or femur) 4, a knee 5, a shin (or tibia) 6, an ankle7 and a foot 8. As illustrated, the patient's thighs are extendedupwardly and positioned between a plurality of thigh positioning posts120 and lower leg positioning posts 125, which restrict translationalmovement of the thigh 4 and lower leg 6. The thigh 4 may also besupported by thigh support 127. The patient's foot 8 is place in an AFOto facilitate rotation of the tibia.

Returning to FIG. 15 apparatus 100 includes a frame assembly 110 and twopivoting assemblies 150 a,b. The components of the frame assembly 110include two base plates 112 a,b, two cross members 114 a,b, a pluralityof thigh positioning posts 120 a-d, a plurality of lower leg positioningposts 125 a-d, a spine member 130, a carriage 135 and a traverse member140. The two substantially rectangular base plates 112 a,b are spaceapart and oriented within substantially the same plane. The based plates112 a,b have a lower surface configure to rest atop a supportingsurface. As one of ordinary skill in the art will appreciate, the baseplates may be fastened to a support surface using fasteners, straps,clamps or other fastening means. Attached to the upper surface of thebase plates are the two parallel and substantially elongate crossmembers 114 a,b. These cross members 114 a,b provide a mounting surfacefor a desired number of positioning posts.

In the illustrated embodiment, cross member 114 a supports four thighpositioning posts 120 a-d. As illustrated, the thigh positioning posts120 a-d are oriented substantially perpendicular to the cross member 114a. The thigh positioning posts 120 a-d are connected to the cross member114 a such that their location may be adjusted and locked at desiredlocations along the length the cross member 114 a. In use, a patient ispositioned into apparatus 100 with their lower thigh proximate the thighpositioning posts 120 a-d. The thigh positioning posts 120 a-d areadjusted to restrict movement of the thighs in a plane substantiallyperpendicular to the longitudinal axis of the patient's femur. Forexample, thigh positioning post 120 a and thigh positioning post 120 bare space apart to receive a patient's thigh. One or both of the thighpositioning posts 120 a-b are then urged against the patient's thigh andlocked in place. The same procedure may be used for thigh positioningposts 120 c-d with respect to the patient's other thigh.

Similar to the thigh positioning posts 120 a-d, in the illustratedembodiment also includes four lower leg positioning posts 125 a-d. Theseposts are connected to the cross member 114 b such that their locationmay be adjusted and locked at desired locations along the length crossmember 114 b. When a patient is positioned in apparatus 100, the lowerleg positioning posts 125 a-d are located just below the knee torestrict translational movement of the tibia.

In one embodiment, a strap (not shown) is provided proximate crossmember 114 a to further restrict movement of the patient's thighs. Thisstrap may be connected relative to cross member 114 a such that whentightened, the thighs are urged toward the cross member 114 a. In oneembodiment, a single strap is used to secure both thighs. Alternatively,one strap for each thigh may be employed. Other embodiments may notinclude this strap.

In an alternative embodiment, a thigh anterior support member 122 may beremoveably secured to the thigh positioning posts 120 a-d afterpositioning the patient's thighs between associated thigh positioningposts. The thigh anterior support member 122 may be urged against thetop of the thigh and locked into place. In one embodiment, the thighsupport bar is sized to extend towards the hip as generally shown inFIGS. 16 and 17. The thigh anterior support member 122 may also extendtoward the knee and contact the knee proximate the patella. In a furtherembodiment, the thigh anterior support member is a bar attached to thethigh positioning posts.

In one embodiment, a thigh support 127 may be positioned intermediatecross member 114 a and 114 b. The thigh support 127 is positionedbeneath the thigh of a patient in use and aids in achieving the desiredangle between the patient's thigh and the supporting surface. The thighsupport 127 may be padded for additional comfort.

Referring to FIG. 23, a torodial restraint 128 may be used to furthersecure the patient's leg. The torodial restraint is positioned proximatethe patella of the knee and attached to the cross members 114 a,b usingstraps 129.

Referring now to FIG. 24, a further embodiment may include an adjustablethigh support 180. As illustrated, the adjustable thigh support 180 isattached relative to the spine 130 and is configured to support theunderside of the patient's thighs. The adjustable thigh support 180includes a support rod 181, a thigh platform 186, a separator 188 and apin 189. The support rod 181 is attached to and extends substantiallyperpendicularly from the spine 130. The support rod 181 defines aplurality of holes 182 space apart along a portion of the length of thesupport rod. The holes 182 are suitably sized to accept a locking pin189.

The platform 186 is a substantially flat member with the separator 188attached to its upper surface. In use, a patient's thighs are positionedatop the platform 186 and are spaced apart by the separator 188. Theheight of the platform and separator assembly above the spine 130 may beadjusted by selectively engaging the locking pin 189 with a suitablysize hole defined by the separator 186 and one of the holes 182 in thesupport rod.

Although the adjustable thigh support 180 is illustrated with anembodiment having a single cross member 114 a, one of skill in the artwill recognize that this support may be used with embodiments havingboth cross member 114 a and 114 b. In this case, the adjustable thighsupport would be positioned intermediate cross member 114 a and 114 b.

Attached proximate the center of the cross member 114 b is one end ofthe substantially elongate spine 130. The spine 130 is orientedsubstantially perpendicular to the cross member 114 b and providessupport for the carriage 135. The carriage 135 is adjustable andlockable using locking member 132 along at least a portion of the lengthof the spine 130. In use, the carriage 135 is adjusted along the lengthof the spine 130 as desired to accommodate differing leg lengths betweenindividual patients and to achieve the desired knee flexion.

In an alternative embodiment, the spine 130 is attached to cross bar 114a and does not include a second cross bar 114 b or base plates 112 a,b.

Transverse member 140 is attached to the carriage b and supports twopivoting assemblies 150 a,b, which is similar to the transverse member47 discussed with reference to apparatus 10. The proximate midpoint ofthe transverse member 140 is attached to carriage 135 and one of thepivoting assemblies 150 a,b is attached proximate each end of thesubstantially elongate transverse member 140. The pivoting assemblies150 a,b are configured similar to pivoting assembly 50 a as describedwith reference to FIG. 7. Apparatus 100 may also include anglemeasurement devices as generally described with respect to apparatus 10.

Referring to FIGS. 15 and 16, the carriage 135 orients the transversemember 140 such that the pivoting assemblies 150 a,b are held at anangle that facilitates positioning of the patient's knee withapproximately 30 degrees of flexion. In one embodiment, the pivotingassemblies 50 a,b are held at a 15 degree angle with respect to thesupport surface. One skilled in the art will appreciate that thepivoting assemblies may be positioned at any desired angle to achieve adesired degree of knee flexion.

Method of Use

As previously discussed, embodiments of the present invention measurethe limb rotation in response to a torque for the purpose of diagnosingligament damage and also to determine the effectiveness of ligamenttreatment. Although concepts embodied in the present invention may beused to measure rotation at any joint, the following discussion willfocus on measuring rotation at a knee joint.

To provide accurate internal and external rotation measurements for theknee joint, the influence of the other joints of the leg need to beminimized. Embodiments of the present invention restrict the motion ofthe other joints associated with the leg such that accurate kneerotation measurements can be taken.

Referring to FIG. 18, the method begins at Step 500 where the patient ispositioned in a supine position with their knees bent and each footsecured to a pivoting assembly. In one embodiment, apparatus 10 ispositioned on a horizontal support surface and the patient is positionedon their back with the spacer support assembly intermediate thepatient's thighs and each of the patient's feet are positioned in anassociated AFO. In one embodiment, the patient's feet are securedindividually to their associated AFOs using straps around both the lowerleg and the foot. In this way, the ankles are substantially immobilizedthereby minimizing any influence of the ankle joints on the rotationalmeasurements.

When using apparatus 10, the lengths of the horizontal member 41 and thesupport column 30 are adjusted for proper alignment of the legs.Preferably, the lengths are adjusted such that the patient's knees arebent at approximately 30 degrees and the patient's shins (or tibias) aresubstantially aligned with the pivoting assemblies. This arrangementhelps to minimize rotation of the thigh when the AFOs are rotated.However, the flexibility of an individual patient may not permit thisalignment, and therefore, the device can accommodate legs in otherconfigurations or flexion angles.

At Step 505, the patient's thighs are secured to minimize the influenceof the femur on the rotational measurements. With apparatus 10, asuitably sized space is positioned on the spacer bar 44. A strap is thentightened around the patient's thighs proximate the spacer 45 such thatthe thighs are urged together and into contact with the spacer.

After securing the patient to the device, rotational measurements can betaken for a first leg at Step 510. In one embodiment, a predeterminedforce is applied in a first direction (e.g., clockwise) and an anglemeasurement is taken. Then, a predetermined force is applied in a seconddirection (e.g., counter-clockwise) and an angle measurement taken. Thisprocedure may then be repeated for a second leg at Step 515. A typicalapplied torque may be 50 inch-pounds; however, any torque desired by theclinician may be applied using embodiments of the present invention.

In an alternative embodiment, a clinician oscillates the pivotingassembly from a predetermined torque in a first direction and then to apredetermined torque in a second direction. The torques for the twodirections may or may not be the same. Torque readings and anglereadings may be taken at predetermined angles, torques or other criteriafor later analysis.

In one embodiment, an analysis tool is utilized to capture torque andangle readings at predetermined time intervals as the clinicianoscillates the pivoting assembly. FIG. 19 provides a screen shot of anexemplary analysis tool that may be used in connection with the presentinvention. When the clinician is ready to collect data, the clinicianselects the appropriate knee and actuates the start test button on thescreen. Then, the clinician oscillates the pivoting assembly betweeninternal rotation and external rotation to a desired torque using atorque application device (e.g., torque wrench or stepper motor). In oneembodiment, the clinician rotates the pivoting assembly clockwise untila torque reading of 40 in-lbs is reached and then rotates the pivotingassembly counter-clockwise until a torque reading of 40 in-lbs isreached.

Meanwhile, torque and angular displacement readings are captured by theanalysis tool at predetermined intervals, such as every 50 milliseconds,as the clinician oscillates the pivoting assembly. When a predeterminednumber of data points are captured, the computer signals that datacollection is complete. At which point, the clinician may repeat thedata capture procedure for the opposite leg.

In one embodiment, the analysis tool plots the raw data onto a graph anddetermines a best fit equation for the raw data. This can be seen in theupper graph in FIG. 19. The lower graph shows two lines associated withthe best fit equation, one for each knee. Also provided in the lowergraph is a slope estimation for the best fit equations.

At Step 520, comparisons are made between the first knee and the secondknee to evaluate relative performance. Assume a patient is experiencingpain in the first knee. The clinician can focus in on discrepanciesbetween the angular measurements of the two knees to aid in diagnosingthe cause of the pain. Furthermore, if treatment has already beenperformed and a significant discrepancy remains, additional treatmentmay be necessary.

When using the analysis tool, the clinician can determine from the lowergraph the neutral angular position of the patient's knees, which isrepresented by the point where the best fit equation crosses the torqueaxis. Or in other words, where the torque value is zero. Furthermore,the slope of the line gives an indication of the “looseness” in theknee. Discrepancies between the neutral angular position and the slopecan indicate an abnormal situation that may require surgery or othertreatment.

Although the above method was described with reference to apparatus 10,the method is equally effective when used in connection with apparatus70 and apparatus 100.

For apparatus 70, the base assembly 80 is positioned on a supportsurface with the two vertical supports substantially perpendicular tothe support surface. The patient is then positioned in the apparatuswith the vertical supports between the patient's thighs and each foot issecured to a pivot assembly. A strap is then tightened against thepatient thigh such that they are urged into contact with the spacer.Data may then be gathered as generally described above.

When data gathering is complete and the patient removed from theapparatus 70, the locking pins may be disengaged and the apparatusfolded to facilitate storage.

When the method is performed using apparatus 100, each of patient'sthighs are positioned between two thigh positioning posts and two lowerleg positioning posts. The patient's feet are then secured to pivotingassemblies. Next, the thigh positioning posts and the lower legpositioning posts are adjusted to restrict motion of the leg proximatethe posts. In one embodiment, a thigh support bar is also urged againstthe top of the thigh proximate the thigh positioning posts. In anotherembodiment, a strap is tightened proximate the thigh support posts toprovide additional restriction of the thigh during measurement. Atorodial restrain may also be employed. One of skill in the art willrecognize that any of these restraint techniques either alone or incombination may be used in connection with embodiments of the presentinvention.

Once the patient is secured to apparatus 100, measurements may be takenas generally described with reference to apparatus 10 above.

Multi-Axis Embodiments

In previously described apparatuses, rotational movement of the tibiaabout the longitudinal axis of the tibia was evaluated. In analternative embodiment, a multi-axis pivoting assembly 200 is used inplace of pivoting assemblies 50 and 150 in the previously describedapparatus. Multi-axis pivoting assembly 200 provides two additionalmovements of the tibia that may be evaluated to obtain a more completeevaluation of the performance of ligaments in the knee.

FIGS. 20 and 21 provide a top and side view, respectively, of multi-axispivoting assembly 200 attached to a transverse member 210. Transversemember 210 is similar to transverse members 47 and 140. Multi-axispivoting assembly 200 includes a first pivoting assembly 220, a secondpivoting assembly 230, a third pivoting assembly 240, a lifting bar 250and a lower leg cuff 255.

The first pivoting assembly 220 facilitates evaluation of translationalmovement of the proximal end of the tibia in a plane substantiallyparallel to the y-z plane as shown in FIGS. 21 and 22. In other words,the first pivoting assembly 220 evaluates relative movement of the tibiain a substantially sagittal plane. The first pivoting assembly 220facilitates this movement by pivoting about an axis substantiallyparallel with the “x” axis as shown. First pivoting assembly 220includes a bushing retainer 221, a bushing 222, a collar 223, a socket224 and a shaft 225 in the same relative arrangement as discussed inrelation to the pivoting assembly 50 a and FIG. 7. However, the shaft225 is attached to plate bracket 226 instead of attachment bracket 56,as described with reference to pivoting assembly 50 a, such that whenthe shaft rotates, the plate bracket 226 rotates. First pivotingassembly 220 also includes a locking pin (not shown) that is configureto selectively engage a suitably sized hole in the attachment plate 226to prevent the first pivoting assembly 220 from rotating.

The second pivoting assembly 230 facilitates evaluation of translationmovement of the proximal end of the tibia in a plane substantiallyparallel with the x-y plane as generally shown in FIGS. 20 and 22. Inother words, the second pivoting assembly 230 evaluates relativemovement of the tibia in a substantially coronal plane. The secondpivoting assembly is rigidly attached to plate bracket 226. The secondpivoting assembly 230 includes a bushing retainer 231, a bushing 232, acollar 233, a socket 234 and a shaft (not shown) in the same generalarrangement as discussed with regard to pivot assembly 50 a and FIG. 7.The bushing retainer 231 is rigidly attached to the plate bracket 226.Similar to the first pivoting assembly 220, the shaft of the secondpivoting assembly 230 is attached to a plate bracket 236, which isoriented within a plane substantially parallel with the “z” axis.Furthermore, the second pivoting assembly 230 includes a locking pin(not shown) that selectively engages a suitably sized hole formed in theplate bracket 236 to prevent rotation of the second pivoting assembly asdesired.

Referring to FIG. 22, the third pivoting assembly 240 is attached to theplate bracket 236 is. The third pivoting assembly 240 facilitatesevaluation of rotation movement of the tibia substantially about itslongitudinal axis (i.e., substantially parallel with the “y” axis). Thisassembly includes a bushing retainer 241, a bushing (not shown), acollar 243, a socket 244 and a shaft (not shown) in the same generalarrangement as discussed in relation to the pivoting assembly 50 a andFIG. 7. The shaft is attached to an attachment bracket 246.

Returning to FIGS. 20 and 21, the lifting bar 250 is substantiallyelongate and attached to the pivot assembly 240 at one end. Attached tothe opposite end is the lower leg cuff 255 with an associated strap 256.To accommodate different leg lengths, the lifting bar B may have anadjustable length. Generally described, the lifting bar 250 applies aforce near the knee when the first pivoting assembly 220 or the secondpivoting assembly 230 is engaged. For example, when the first pivotingassembly 220 is engaged and rotated, the two plate brackets 226 and 236are also rotated causing the lifting bar to pivot. This pivoting actioncauses a force proximate the lower leg cuff under the lower legproximate the knee.

Although the illustrated multi-axis pivoting assembly 200 includes threeindividual pivot assemblies, one of skill in the art will appreciatethat other embodiments of the present invention may include a singlepivoting assembly or any combination of the three pivoting assembliesdescribed above.

Methods of Use for the Multi-Axis Pivot Assembly 200

As discussed above, the multi-axis pivoting assembly 200 allows aclinician to evaluate the performance of a knee in three differentdegrees of freedom. The following paragraphs will generally describeevaluating ligaments in the knee using the three different pivotingassemblies of the multi-axis pivoting assembly. It should be understoodthat a clinician may desire to only use one or two of the possible threepivoting assemblies to evaluate the knee.

Before evaluating knee ligaments using the multi-axis pivot assembly200, the patient is place in either apparatus 10, 70 or 100. Of course,the pivoting assemblies 50 a,b in those devices would be replace withthe multi-axis pivot assembly 200. With each apparatus, the patient'sfeet are placed in the AFOs and their thighs are secured to theapparatus. In addition, the patient's lower leg is secured to the lowerleg cuff.

To evaluate the translational movement of the tibia in a directionsubstantially parallel with the y-z plane, the locking pin in the firstpivoting assembly 220 is disengaged and the locking pin in the secondpivoting assembly 230 is engaged. At this point, a torque is applied tothe first pivoting assembly 220 causing the AFO and lifting bar 250 topivot as well. This pivoting action causes a force to be appliedproximate the lower leg cuff 255 causing the proximal end of the tibiato move in relation to the femur.

The amount of linear movement of the tibia may be determined in avariety of ways. For example, an inclinometer may be applied to thelifting bar 250 or the patient's lower leg to determine the angle of thepatient's tibia with respect to the direction of gravity at differingtorques. Using this data, the angular displacement can be calculatedwith regard to the length of the lifting bar 250. In another embodiment,the rotation angle of the first pivoting assembly is measured using apotentiometer or other angular displacement measuring device. Of coursea linear displacement sensor may be placed proximate the tibia near theknee to manually or automatically measure the linear displacement of thetibia in response to the applied force with respect to the femur orother reference frame.

For evaluation purposes, the linear displacement may be evaluated withregard to torque applied or the torque applied may be converted to aforce at the end of the lifting bar 250 if desired.

To evaluate the translational displacement in a plane substantiallyparallel with the x-y plane in response to a given force, the lockingpin of the first pivoting assembly 220 is engaged such that it does notpivot and the locking pin of the second pivoting assembly 230 isdisengaged to allow pivoting. Next, a torque is applied to the secondpivoting assembly 230 thereby causing a force to be applied at the kneein a direction substantially parallel with the “x” axis. To determinethe displacement of the tibia proximate the knee, the angulardisplacement of the pivoting assembly may be measured using apotentiometer or other angular displacement measuring device. Thisangular measurement result may then be translated to a linear distanceusing the length of the lifting bar if desired. Alternatively, thelinear displacement may be measured manually or automatically using alinear displacement sensor or other measuring device with reference tothe femur or other reference frame. In one embodiment, lineardisplacement data is gathered for different force values or torquevalues to determine the performance of the ligaments in the knee.

Finally, to evaluate the rotational performance of the knee in responseto a torque applied about the longitudinal axis of the tibia, thelocking pins of both the first pivoting assembly 220 and second pivotingassembly 230 are engaged thereby preventing pivoting of the first andsecond pivoting assemblies 220, 230, respectively. Next, a torque isapplied to the third pivoting assembly as generally described withrelation to apparatus 10, 70 and 100.

CONCLUSION

In concluding the detailed description, it should be noted that it wouldbe obvious to those skilled in the art that many variations andmodifications can be made to the preferred embodiments withoutsubstantially departing from the principles of the present invention.Also, such variations and modifications are intended to be includedherein within the scope of the present invention as set forth in theappended claims. Further, in the claims hereafter, the structures,materials, acts and equivalents of all means or step-plus functionelements are intended to include any structure, materials or acts forperforming their cited functions.

It should be emphasized that the above-described embodiments of thepresent invention, particularly any “preferred embodiments” are merelypossible examples of the implementations, merely set forth for a clearunderstanding of the principles of the invention. Any variations andmodifications may be made to the above-described embodiments of theinvention without departing substantially from the spirit of theprinciples of the invention. All such modifications and variations areintended to be included herein within the scope of the disclosure andpresent invention and protected by the following claims.

That which is claimed:
 1. An apparatus for evaluating a knee of apatient, the patient having a femur, a tibia, and a foot, the apparatuscomprising: a frame; a foot accepting element configured to secure atleast a portion of the foot; a multi-axis pivoting assembly attached tothe frame and the foot accepting element, the multi-axis pivot assemblycomprising first and second pivot subassemblies configured to transferfirst and second torques to the tibia causing pivoting movement of thetibia relative to the femur about first and second axes, respectively; afirst angle measuring device attached to the first pivot sub-assemblyand configured to measure angular displacement of the first pivotsub-assembly in response to the first torque; and a second anglemeasuring device attached to the second pivoting sub-assembly andconfigured to measure angular displacement of the second pivotsub-assembly in response to the second torque; wherein: the first axisis distal to the foot accepting element; and the second axis issubstantially parallel with a longitudinal axis of the tibia.
 2. Theapparatus of claim 1, wherein the pivoting movement about the first axislies in a substantially sagittal plane.
 3. The apparatus of claim 1,further comprising an elongate lifting bar having a first end attachedto the first pivot subassembly and a second end configured to beattached to the patient between the knee and the foot such that thepivoting movement about the first axis applies a force to the tibia viathe lifting bar.
 4. The apparatus of claim 1, wherein the multi-axispivoting assembly comprises a third pivot subassembly causing pivotingmovement of the tibia relative to the femur about a third axis.
 5. Theapparatus of claim 4, wherein the pivoting movement about the third axislies in a substantially coronal plane.
 6. The apparatus of claim 4,wherein the first, second, and third axes are substantiallyperpendicular to one another.
 7. The apparatus of claim 1, furthercomprising an elongate lifting bar having a first end attached to thefirst pivot subassembly and a second end configured to be attached tothe patient between the knee and the foot such that the pivotingmovement about the first axis applies a force to the tibia via thelifting bar.
 8. The apparatus of claim 1, further comprising an analysistool to capture torque readings of the first and second torques.
 9. Theapparatus of claim 8, wherein the torque readings are captured atpredetermined time intervals.
 10. An apparatus for evaluating a knee ofa patient, the patient having a femur, a tibia, and a foot, theapparatus comprising: a frame; a foot accepting element configured tosecure at least a portion of the foot; a multi-axis pivoting assemblyattached to the frame and the foot accepting element, the multi-axispivot assembly comprising first and second pivot subassembliesconfigured to transfer first and second torques to the tibia causingpivoting movement of the tibia relative to the femur about first andsecond axes, respectively; a first angle measuring device attached tothe first pivot sub-assembly and configured to measure angulardisplacement of the first pivot sub-assembly in response to the firsttorque; and a second angle measuring device attached to the secondpivoting sub-assembly and configured to measure angular displacement ofthe second pivot sub-assembly in response to the second torque; wherein:the first axis is distal to the foot accepting element; the pivotingmovement about the second axis lies in a substantially coronal plane;and the first and second axes are perpendicular to one another.
 11. Theapparatus of claim 10, wherein the pivoting movement about the firstaxis lies in a substantially sagittal plane.
 12. The apparatus of claim10, further comprising an elongate lifting bar having a first endattached to the first pivot subassembly and a second end configured tobe attached to the patient between the knee and the foot such that thepivoting movement about the first axis applies a force to the tibia viathe lifting bar.
 13. The apparatus of claim 10, further comprising ananalysis tool to capture torque readings of the first and secondtorques.
 14. The apparatus of claim 13, wherein the torque readings arecaptured at predetermined time intervals.
 15. An apparatus forevaluating a knee of a patient, the patient having a femur, a knee, atibia, and a foot, the apparatus comprising: a frame; a foot acceptingelement configured to secure at least a portion of the foot; amulti-axis pivoting assembly attached to the frame and the footaccepting element, the multi-axis pivot assembly comprising first,second, and third pivot subassemblies configured to transfer first,second, and third torques to the tibia causing pivoting movement of thetibia relative to the femur about first, second, and third axes,respectively; a first angle measuring device attached to the first pivotsub-assembly and configured to measure angular displacement of the firstpivot sub-assembly in response to the first torque; and a second anglemeasuring device attached to the second pivoting sub-assembly andconfigured to measure angular displacement of the second pivotsub-assembly in response to the second torque; wherein: the first axisis distal to the foot accepting element; the second axis issubstantially parallel with a longitudinal axis of the tibia; and thethird axis is perpendicular to the first and second axes.
 16. Theapparatus of claim 15, wherein the pivoting movement about the firstaxis lies in a substantially sagittal plane.
 17. The apparatus of claim15, further comprising an elongate lifting bar having a first endattached to the first pivot subassembly and a second end configured tobe attached to the patient between the knee and the foot such that thepivoting movement about the first axis applies a force to the tibia viathe lifting bar.
 18. The apparatus of claim 15, wherein the pivotingmovement about the third axis lies in a substantially coronal plane. 19.The apparatus of claim 15, further comprising an analysis tool tocapture torque readings of the first and second torques.
 20. Theapparatus of claim 19, wherein the torque readings are captured atpredetermined time intervals.